Some embodiments described herein relate generally to micromechanical structures that can detect angular rates and are sensitive, robust and insensitive to temperature. In particular, some embodiments can use two vibrational modes of a resonating structure where the first mode is used as the excitation mode, and the gyroscopic effect causes the excitation of the second mode, which can be detected by a circuit having an output proportional to the angular rate about a given axis.
Gyroscopes are of interest for navigation systems, motion control of robots and automated manufacturing, entertainment electronics, and medical applications. A gyroscopic sensor measures the angular rate .omega. around one or several defined axes, being x, y, or z, and produces a voltage at the sensor output that is proportional to the angular rate.
A gyroscope can use a variety of sensor effects, i.e. optical, electrical, acoustic, and mechanical.
The simplest design for a known gyroscope exploiting a mechanical sensor effect is to use a cantilever clamped at one end having a square cross-section. The cantilever is excited to vibrate up and down. If there is a rotation around the center of the cantilever it will start to vibrate left and right. The amplitude of this secondary vibration from left to right can be measured and is proportional to the angular rate.
The difficulties for a known gyroscope, however, include sensitivity towards acceleration, vibration, shock, drift of the sensor, temperature sensitivity, cross-coupling of the two ideally orthogonal modes etc. Thus, a need exists for improved gyroscopes.